Means for compensating for disturbances of earth potential.



J. W. MILNOR.

MEANS FOR COMPENSATING FOR DISTURBANCES OF'EARTH POTENTIAL.

APPLICATION mm mm. l0. IQH- Patented; Jan. 29', 1918.

A TTORNEY- INVEALTORQ v 7M1.

UNITED STATES PATENT OFFICE.

.Losnmr w. Mnmoa'or new YORK, N. r assxcnon ro THE WESTERN UNION T ELE- amen QMPANY, or NEW YORK, N. Y., A coarona'rron or NEW YORK.

MEANS FOR COMPENSATING FOR DISTURlBANCES F EARTH POTENTIAL.

To all whom it may concern: .Be it known that I, JosnPJ-I W'. MIL'NOR, a citizen of the United Statesof America, and a resident of- New York, county of Now York, and State of New York, have invented certain new and useful Means for Compensating for Disturbances of Earth Potential,

of which the following 'is a specification. This invention'relates to means for compensating for differences of. potential between the ground connections at the two ends of a system of electrical communication, such for example, as a telegraph system, and comprises a generator'located in one of the ground connections ofthe system,

together with novel (ontrol means for that,

' generator, andother features all as hereinafter described and particularly pointed out in the appended claims.

simple and reliable means forcompensating for] differences ofpotential between the grounds at the two ends of a system of communication, and, to avoidany periodic oscillation ofpotential due to the action of the compensating means itself.

I I will nowgproceed to' describemy invention with reference to the accompanying drawing,'in which. Figure 1 is a diagram illustrating diagrammatically a compensat- -ing arrangement er'nl'iodying my invention, in connection with' systems of communicationextendin which the'di erences of potential exist; and F igL 2 is'a' fragmentary diagram illustrating an alternative arrangement.

ntheoperation oftelegra'ph systems, tel- 'ephone systems, and the like. much trouble of potential between-the grounding points of the system, which difieren'ce of potential is commonly 'due to neighboring electric railways or electric power circuits or the like."- I This difference of potential, due to causes external to the system' qi communication, is frequently variable, which makes'correction for such difference of potential by ordinary means,'yet more difficult. By the present the line Wires of systems of ccfnr'nunication Specification of Letters Patent.

The object of my inrention is to provide 3 ving for, the actual difference in earth between the points between is frequently experienced due -to a differenceate grounding bus-bars at the Patented Jan. 29, 1918.

Ap lication filed March 10,1917. Serial No. 153,824.

extending from the o1ie.'bus-bar to the other.

At the ends of these conductors 3 and a I have shown, diagrammatically, the trans mitting and receiving arrangements of ordinary duplex telegraph systems, such transmittingand receiving arrangements being too .wellfknown to require description here. The systems of communication of wires 3 and 4 are entirely separate and distinct, and there may be as many of these systems between bus-bars 1 and 2,- as desired nor need these systems of communication be of the same nature; that is to say, one might be a telegraph system and the. other or others telephone systems.

5 designatesan earth. connection for busbar 1, and 6 designates a generator interposedin that ground connection, 7 being I the field windings of that generator. 8 designates the ground connection for bus-bar 2. It will be'apparent that generator'ti, if properlycontrolled and operatechwill create a potential, equal and opposite to the earth .potntial existing between ground. connec -I tions 5 and 8, so neutralizing, or compensatpotential between-points 5 and 8.

9 designates a'polar relay having two magnet -windings .10 and 11. For convenience in illustration, these two windings 10 and 11 are shown as on separate spools;

butin practice, and as is well known, these windingswill commonly be located on the samespools. Winding 10 is located in a conductor 12 leading from bus-bar I to some point 13, at which no potential disturbance exists. This point 13 i's usually a point 1ocated laterally with respect to the 'condu'c- 'a. point which is either in a direct line hetween points 1 and 2,,or a. oint close to the line conductors 3 and 4'. hiding-.11; is in tors 3 and 4; that is to say it is not usually a circuit comprising a conductor 14 extend,

ing through a .coil l5 in inductive relation with respect to the field coil 7' of generator. 6: the circuit thence extending through-com .ductor 16 back to winding 11. It will I apparent that .contim ia-l reversalof the polari ty of the current passing through field 5 I coil. 7 will induce currents of opposite d i-- rection in coil 15 and circuit 14:-16, so causing yihra-tion of the armature of relay'l); The field coil 7 of generator 6 is connected to the armature of. a polar relay 17, the cir:

cuit thence passing through said armature and the one contact stop or the other of the relay, and through one or the other of two opposed batteries 18 and 19, back to the coil 7. The magnet winding of relay 17 is in a (.:ircuit passing through the armature of one or the other of the opposed contact stops of relay 9, and thence through one or the other of opposed batteries 20 and 21, back to the magnet wilulings of said relay 17.

The action which results with the circuit. arrangements thus described, is as follows: Assume that there is no currentin the windings of relay 9, 'If at a given in stant the tongue of relay '9 touches its upper contact there will be'a current through battery 21 and the magnet \-\-'indings of relay 17 tending, We will say, to more thearmature of relay 1'? to the right. As soon as this armature touches its right hand-contact poin't current will pass in one direction through field coil 7 of the generator 6; andthe consequent energization of field coil 7 will induce a current flow in the inductively-associated coil which current. transmitted through conductors" 1 1 and 16, will act through magnet coil 11 of Xen a to reverse the armature of that relay, there by in turn reversing the magnetization of the coil of relay 17 and so in turn reversing for that bus-bar, such generator being ingenerator. In practical use of this former system referred to it has been found that the potential of the corrected busbar osso cillates about the mean potential, instead of being steady. In one case the oscillation was found to be equivalent to an alternat ing current potential of about ten volts with a frequency of about fifteen cycles per sec 5) ond; the potential being between the con rected bus-bar and the true earth. The cause of this oscillation of potential is undoubtedly the inductancoof the field circuit of the generator, giving to that field :11! circuit a certain time factor, and the time factor of the relay determined in part by its adjustment. By the present invention, this existence of a normal period of the field circuit producing .a potential oscillation 95 i the position of the armatu'reof that 1 elay,I"s11 cl;i as described, is avoided; the' relay 9 thereby inducing a current in the opposite directlon 1n coil 15 and so reversing the po 'sition of the armature of'r'elay 9. It will be apparent that, with no current passing through coil 10 of relay 9,'t hc armatures of the two relays yilira'te continually. Since. due to the large self inductance of generator field Winding 7, a comparatively long time .(perhapsone second or more) is required to effect a considerable change in the current flowing through it, it is evident that the rapid vibrationsjof the relays can cause only exceedingly small oscillations of the current in those field windings 7.

If there be 7a currentin Winding 10. of relay 9, due to difference of potential between the corrected bus-bar 1 and the true earth' potential at 13, the armati'ireor tongue of relay 9 will tend to rest against its one contact. or the other (according to the direction of current in conductor 12) a greater length of time than it does against .theother cq'inta'ct of that relay. As a result, the tongue of relay 17 will also tend to rest against one contact a greater length of time thanagainst the other, thus enabling the current in generator field winding 7 to build up to a" value sufii'cient to cause the generator to compensate for the difference in potential between bus-bar 1 and ground 13. V H'cretofore a system for equalizing the potentials of grounding points has been devised, wherein a generator is interposed be-.

t-"\ r one terminal .bus-bar and the ground 'eing'self yihratory. (except as its normal ibnations a're checked by current through the circu'i nd"windings 10) has a relatively .l i'gh la g s o that the batteries 16 and loo 1? affect-the fie d windings 7 of the genera tor 6 not at all, practically, unless'there be a distinct current flow in conductor 12 and windings 10 tending to cause the armature of relay 9 to linger against one stop or the 10) other, and so causing the armature of relay 1'? to correspondingly linger.

It is not necessary that two cooperating relays, such as relays 9 and 17, be employed for clfl'ecting the rapidly recurring -reversal no of the field circuit 7 of generator 6. In Fig.2 I illustrate an arrangement wherein a single relay 9 is employed for this purpose. In this-figure, 'as in Fig. 1, 1 designates a correcting bus-bar of the-system, 6 the, correcting generator, 7 and 15. co5perating field coils, of the generator, 91 the relay referred to having magnet coils 10 and the current infield coil 7 is reversed, the

current-induced in field coil 15, as a resultof such reversal, acts through magnet coil llitpon the armature of relay ,9 to maintain such vibration. The action of the control circuit 12 on the relay is the same as in Fig 1. Resistance shunts-22 and 23 connect field coil 7 withjbatteries 20 and 21 respecfl from one point of such system tojagroundtively. l a

In a companion application, Serial No. 153,822, I have claimed the method of compensating for earth potential disturbance, and the method of preventing oscillation of potential due to the resonance of the field rial No. 153,822.

circuit of the generatoritself, carried out by the apparatus above described; and in such other application I have also claimed means,

alternative to the means herein illustrated and described, for effecting correction of earth potential and forpreventing cyclic dis erator itself. In still another companion ap' plicatiom'Serial No. 153,823, I have claimed still other means for correcting for disturba-i'lce of earth potential and for preventing cyclic disturbance of potential due to the correcting generator itself. The claims generic to the said Narious embodiments of my invention are included in application Se- The means for preventing the hunting of the correcting generator, 7). e., the impressing of a voltage oscillation by the corresting generator itself, above described, is not confined to the'prevention of,'or correction or compensation for, direct current ground potential disturbance, but is applicable also to the preventionof such hunting action in the case of correction for alternating current electro-magnetic induction, or alternating current ground potential; andin my companion application, Serial No. 153,825, I have shown means for preventing the hunting action'of my companion. application, Serial No. 153,822, employed for correction for alternating current disturbances. The substitution of the means for" preventing hunting action, herein described, for the particular means for the purpose shown in my said application, SerialNo, 153,825, is obvious in view of the relations between the disclosures present application and that of my applica- 'tion' Serial'No. 153,822 In 'suchuse of the presentinvention for correction of alternat- 1ng current disturbance, a control circuit,

like the control circuit 12, herein illustrated and described,-will be employed, sucha control circuit being exposed to the influence of the alternating current disturbance, just as, in the resent application, the control circuit 12 s exposed to the ground potential.

of the \Vhat I claim is: 1. A round connection for a system of communication COIIIPI'lSlIlg' a connectlon ing point at which'disturbances of earth po tentlal may exist; a generator 1n such ound connection having a COIltI'OlllIl' fie d= c1r emit, a source of currentsupp y therefor,

two relays, one of said relays arranged by its vibration to reverse the current 1n said field circuit, a coil inductively. .associated with respect to said enerator field circuit and connected operatively with a magnet circuit of the second relay, to cause such second relay to vibrate, said second'relay provided with means for causing said first menmeans in vibration, said relay means havin a controlling magnet in addition to thatcol by which it is caused to vibrate. i

Ina system of communication comprisrect. for external disturbances imparted to the system, the combination with a correcting generator having a controlling field circuit, relay means arranged .by. its vibrationto reverse the current in said fieldcircuit,

said relay means having an operating magnet, a coil inductively associated with sald' generator field circuit, and connected operatively with said magnet to cause the vibration of such relay means, such relay means having also another control magnet, and a control circuit subjected, like such system of communication, to the disturbance, and pass ing through such controlling magnet.

In testimony'whereof I have signed this enerator having a coning a correcting generator arranged to-cor- I specification in the presence of twosubscribing' Witnesses.

JOSEPH W. MILNOR.

Witnesses:

H. M, MARBLE, PAUL H. FRANKE. 

